Celestial happenings you can see from your own backyard

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Lyrid meteor shower will make you think big

A brilliant meteor flashes across the sky. Will this weekend's Lyrid meteor shower shower us with a few of these beauties? Lyrids are known for their occasional fireballs. Credit: John Chumack

The annual Lyrid meteor shower peaks tonight (Saturday) through Sunday morning April 21-22. While a minor shower, the Lyrids serve as a “season opener” to the bigger shows coming in mid-August and December.

Every year in April Earth passes through the dust and debris left behind by past visits of Comet Thatcher. Illustration: Bob King

The comet takes 415 years to make a single trip around the sun, so there’s no hope of any of us seeing it in our lifetimes. But we can see little bits of it that were left behind long ago.

Each time a comet swings by the sun, it drops lots of dust, fluffy ice and pebbly pieces in its wake. The third week of April every year Earth plows through debris ranging in size from sand grains to small pebbles left behind during Thatcher’s previous flybys. When a lucky mote strikes the atmosphere, it vaporizes in a flash of light called a meteor or shooting star.

When you’re out watching the show, consider that the average speed of a Lyrid meteor is 30 miles per second or 108,000 miles per hour. At that velocity, a bit of dust or small pebble burns to ash through friction. The luminous trail we call a meteor is mostly light given off by atoms in the upper atmosphere some 70 miles high. The fast-moving comet debris excites or ionizes the atoms; when they return to normal microseconds later they emit billions of photons of light we see as a bright streak or “falling star”.

In a flame test, sodium burns a brilliant yellow. Sodium is common in some meteorites. Credit: Soren Wedel Nielsen

A typical meteor trail is less than 3 feet in diameter but tens of miles long. Think of it as glowing tube overhead.

When the comet particle burns up, it can give off different colors depending on its composition. Sodium flares bright yellow; magnesium is blue-white and nickel a lovely emerald green to name a few. Speed also factors into color. The faster the meteor, the more energy it imparts to the air and the whiter and bluer the streak will be. Slower meteors blaze orange and red.

The Lyrids are named after Lyra the Harp, the constellation from which they appear to originate. The origination point is called the radiant, and you can see from the map it’s not far southwest of Lyra’s brightest star Vega, making it easy to pinpoint. The radiant is the direction Earth is moving toward as it slices through Comet Thatcher’s debris.

Snow appears to radiate from straight ahead as seen through your windshield when you drive into a storm. Meteor showers appear to radiate from one point in the sky because Earth is traveling "into the storm" just like your car. Photo: Bob King

Similar to seeing snow or rain appear to originate from a point ahead of you when you’re driving straight into it, the meteors stream out and away from the radiant. Lyrids closest to the radiant are short, slow stubs of light while those further off stretch into longer streaks.

News is all good for this year’s Lyrids. No moon to interfere and the shower maximum occurs Sunday morning, which for many of us is the weekend. From a dark sky expect to see 10-12 meteors per hour. If you have any doubt as to whether they’re Lyrids or just random meteors, trace their paths backwards and if they point toward Vega, you’ve caught one.

This map shows the sky early Sunday morning with Vega and the Lyrid radiant well up in the eastern sky. Face your lawn chair east or south for the best view. Created with Stellarium

To see the shower best Vega and the radiant should be well up in the northeastern sky. For observers in the U.S. and Canada, you can start watching around 12:30-1 a.m. Sunday. Numbers should pick up as the radiant rises higher and higher until dawn.

I like to flop out in a folding chair under a warm blanket. Don’t get too comfortable though – you might fall asleep! Having a friend join you is a great way to stay alert. It also puts the conversation in a larger, more cosmic context. I’ve found that almost everyone thinks bigger thoughts under a starry sky than when seated inside a building.

In a related story, this weekend, NASA scientists, amateur astronomers, and astronaut Don Pettit on board the International Space Station will attempt the first-ever 3D photography of meteors from Earth and space. Read about it HERE.

About astrobob

My name is Bob King and I work at the Duluth News Tribune in Duluth, Minn. as a photographer and photo editor. I'm also an amateur astronomer and have been keen on the sky since age 11. My modest credentials include membership in the American Association of Variable Star Observers (AAVSO) where I'm a regular contributor, International Meteorite Collectors Assn. and Arrowhead Astronomical Society. I also teach community education astronomy classes at our local planetarium.

For those of us in the Central timezone who are novices at this, is 12-1 still the best time to see them? I heard that Mars and Saturn will be particularly bright as well, so I want to be able to see it all.

Smoore,
The radiant is up high enough to start watching around 12-1 a.m. time. The number of meteors will increase the closer to dawn it gets, since the radiant will have risen higher by then. But yes, anyone in any time zone can start looking around midnight.